Heterogeneity of DNA content and expression of cell cycle genes in axenically growing Entamoeba histolytica HM1:IMSS clone A

Gangopadhyay, Samudra S.; Ray, Sib Sankar; Kennady, Kavin; Pande, Gopal; Lohia, Anuradha

doi:10.1016/s0166-6851(97)00156-4

Cited by 35 publications

(43 citation statements)

References 16 publications

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“…The cells no longer had synchronized levels of surface EhMSP-1 exposure after 12.5 h, since high and low populations were again present (data not shown). As has been previously reported (22), serum starvation resulted in a more homogeneous distribution of amebic DNA content (by propidium iodide staining), but cell division as assessed by CFSE staining was not directly linked to DNA content (data not shown). Given this, it was not possible to determine whether EhMSP-1 surface abundance is linked to cell cycle or whether synchronization following serum starvation was simply a stress response.…”

Section: Fig 6 Ehmsp-1 Silencing Reduces E Histolytica Motility (A)supporting

confidence: 73%

“…Serum starvation has been shown to induce translocation of an E. histolytica Rab protein (EhRab11) to the cell periphery, to affect expression of several genes, and to partially synchronize the cell cycle of E. histolytica trophozoites in axenic culture (22,30,36,49). We therefore examined whether serum starvation influenced surface exposure of EhMSP-1.…”

Section: Fig 6 Ehmsp-1 Silencing Reduces E Histolytica Motility (A)mentioning

confidence: 99%

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Control of Entamoeba histolytica Adherence Involves Metallosurface Protease 1, an M8 Family Surface Metalloprotease with Homology to Leishmanolysin

et al. 2012

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ABSTRACTInvasive amebiasis due toEntamoeba histolyticainfection is an important cause of morbidity in developing countries. TheE. histolyticagenome contains two homologues to the metalloprotease leishmanolysin gene,Entamoeba histolytica MSP-1(EhMSP-1) andEhMSP-2, while the commensal amebaEntamoeba disparhas lostEhMSP-1. In this study, we sought to characterizeE. histolyticametallosurface protease 1 (EhMSP-1). Using immunoprecipitation and a model substrate, we found that EhMSP-1 was a functional metalloprotease. Confocal microscopy and flow cytometry revealed that EhMSP-1 localized to the cell surface and revealed the existence of distinct, nonclonal trophozoite populations with high and low EhMSP-1 surface abundance that became synchronized following serum starvation. Phenotypic assays were performed after silencingEhMSP-1. Adherence of EhMSP-1-deficient trophozoites to tissue culture cell monolayers was more than five times greater than that of control amebas, but surface staining of several antigens, including the galactose adherence lectin, was unchanged.EhMSP-1silencing similarly increased adherence to both viable and apoptotic Jurkat lymphocytes. Tissue culture cell monolayer destruction was reduced byEhMSP-1silencing, although it was blocked almost completely by inhibiting cysteine proteases. Consistent with a primary defect in regulation of amebic adherence,EhMSP-1silencing also resulted in reduced mobility on tissue culture cell monolayers and in increased phagocytosis. In conclusion, EhMSP-1 was shown to be a surface metalloprotease involved in regulation of amebic adherence, with additional effects on cell motility, cell monolayer destruction, and phagocytosis.

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Section: Fig 6 Ehmsp-1 Silencing Reduces E Histolytica Motility (A)supporting

confidence: 73%

Section: Fig 6 Ehmsp-1 Silencing Reduces E Histolytica Motility (A)mentioning

confidence: 99%

Control of Entamoeba histolytica Adherence Involves Metallosurface Protease 1, an M8 Family Surface Metalloprotease with Homology to Leishmanolysin

et al. 2012

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“…Our previous studies have shown that an increased population of cells with 4ϫ or more genome contents identified by flow cytometry could be due to an increase in the number of multinucleated cells or in the number of genome copies in uninucleated cells (12,13,18). An increase in the number of multinucleated cells signifies a delay in cytokinesis, while an increase in the DNA content of individual nuclei suggests Increased expression of Ehformin-1 and -2 delays both cell division and mitosis.…”

Section: Resultsmentioning

confidence: 99%

“…Log-phase cultures may accumulate multinucleated cells containing heterogeneous amounts of DNA (12,18). Our previous observations suggest that genome reduplication without mitosis and irregularity in cytokinesis contribute maximally to the observed heterogeneity (12,36).…”

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confidence: 94%

Entamoeba histolytica Encodes Unique Formins, a Subset of Which Regulates DNA Content and Cell Division

Majumder

Lohia

2008

Infect Immun

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The formin family of proteins mediates dynamic changes in actin assembly in eukaryotes, and therefore it is important to understand the function of these proteins in Entamoeba histolytica, where actin forms the major cytoskeletal network. In this study we have identified the formin homologs encoded in the E. histolytica genome based on sequence analysis. Using multiple tools, we have analyzed the primary sequences of the eight E. histolytica formins and discovered three subsets: (i) E. histolytica formin-1 to -3 (Ehformin-1 to -3), (ii) Ehformin-4, and (iii) Ehformin-5 to -8. Two of these subsets (Ehformin-1 to -3 and Ehformin-4) showed significant sequence differences from their closest homologs, while Ehformin-5 to -8 were unique among all known formins. Since Ehformin-1 to -3 showed important sequence differences from Diaphanous-related formins (DRFs), we have studied the functions of Ehformin-1 and -2 in E. histolytica transformants. Like other DRFs, Ehformin-1 and -2 associated with F-actin in response to serum factors, in pseudopodia, in pinocytic and phagocytic vesicles, and at cell division sites. Ehformin-1 and -2 also localized with the microtubular assembly in the nucleus, indicating their involvement in genome segregation. While increased expression of Ehformin-1 and -2 did not affect phagocytosis or motility, it clearly showed an increase in the number of binucleated cells, the number of nuclei in multinucleated cells, and the average DNA content of each nucleus, suggesting that these proteins regulate both mitosis and cytokinesis in E. histolytica.Polymerization of actin into helical filaments is nucleated by different groups of actin-binding proteins, which in turn are controlled by specific signaling molecules in eukaryotic cells (10, 66). Currently, the three known groups of F-actin nucleating factors are the Arp2/3 complex, formins, and spire (10, 21). Formin homology proteins promote rapid assembly of unbranched actin filaments and local reorganization of higherorder cellular structures to execute specified cytoskeletal functions (reviewed in reference 21). These multidomain proteins have many isoforms that are ubiquitously expressed and perform diverse cellular functions in almost all eukaryotic cells, from vertebrates and plants to unicellular protists (25). The defining feature of formin proteins is the formin homology 2 (FH2) domain, which is required for the nucleation and elongation of nascent actin filaments (24,43,46). The FH1 domain, preceding the FH2 domain, is another key region found in most formins and is made up of tandem repeats of proline and other amino acids (24). Polyproline residues in the FH1 domain interact with profilin to recruit assembly-competent actin monomers in the vicinity of the FH2 domain (50, 52, 61). The FH1 domain also interacts with Src homology 3 (SH3) domainor WW domain-containing proteins (17, 59). Thus, the core FH1-FH2 region nucleates unbranched actin filaments, unlike the Arp2/3 complex, which creates branched filaments (21). Other regulatory domains,...

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“…The average DNA content of an asynchronous cell population fluctuates between 1x-6x genome contents (Gangopadhyay et al 1997a). Multiple genome contents maybe present in a single nucleus or distributed over multiple nuclei in a single cell .…”

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confidence: 99%

Genome Re-duplication and Irregular Segregation Occur During the Cell Cycle of Entamoeba histolytica

et al. 2007

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Heterogeneity of genome content is commonly observed in axenic cultures of Entamoeba histolytica. Cells with multiple nuclei and nuclei with heterogenous genome contents suggest that regulatory mechanisms that ensure alternation of DNA synthesis and mitosis are absent in this organism. Therefore, several endo-reduplicative cycles may occur without mitosis. The data also shows that unlike other endo-reduplicating organisms, E.histolytica does not undergo a precise number of endo-reduplicative cycles. We propose that irregular endo-reduplication and genome partitioning lead to heterogeneity in the genome content of E.histolytica trophozoites in their proliferative phase. The goal of future studies should be aimed at understanding the mechanisms that are involved in (a) accumulation of multiple genome contents in a single nucleus; (b) genome segregation in nuclei that contain multiple genome contents and (c) maintenance of genome fidelity in E. histolytica.

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Heterogeneity of DNA content and expression of cell cycle genes in axenically growing Entamoeba histolytica HM1:IMSS clone A

Cited by 35 publications

References 16 publications

Control of Entamoeba histolytica Adherence Involves Metallosurface Protease 1, an M8 Family Surface Metalloprotease with Homology to Leishmanolysin

Control of Entamoeba histolytica Adherence Involves Metallosurface Protease 1, an M8 Family Surface Metalloprotease with Homology to Leishmanolysin

Entamoeba histolytica Encodes Unique Formins, a Subset of Which Regulates DNA Content and Cell Division

Genome Re-duplication and Irregular Segregation Occur During the Cell Cycle of Entamoeba histolytica

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